Device and method for cleaning parts of a boat immersed in water

ABSTRACT

An apparatus for cleaning the underwater portions of a boat having at least one cleaning unit with an ejection element for generating a jet of cleaning fluid under high pressure, and a manifold for generating jets of gas under low pressure. The manifold enables a space to be defined around the cleaning fluid jet in which space density is considerably reduced relative to the density of the surrounding water, such as a space that is free or practically free from water; this space extends from the ejection element to the surface for cleaning of the underwater portions. The apparatus is applicable to cleaning boats, such as sail boats, motor boats, and canal boats, without it being necessary to take them out of the water.

This is a nationalization of PCT/FR01/03758 filed Nov. 28, 2001 andpublished in French.

The present invention relates to a method of cleaning underwaterportions of a boat, which method can be implemented without it beingnecessary to take the boat out of the water.

The invention also provides cleaning apparatus enabling the method to beimplemented.

The underwater portions of a boat, and in particular of the hull, thekeel, and the cheek of the rudder, are generally protected by applying aspecial “antifouling” paint thereto. Such paint gives off toxic agents(copper oxides, mercury arsenate) which slow down the proliferation andthe fixing of seaweed and shell-fish to the hull of the boat.Nevertheless, the effectiveness of such paint is limited in time andresidues of the paint together with the seaweed and shell-fish that havenevertheless managed to become fixed to the hull need to be removedperiodically prior to applying a new layer of antifouling paint.

In addition, it is necessary to keep a hull clean in order to maintainthe performance and the speed of the boat while sailing.

The hull is generally cleaned by mechanical means such as brushes,tools, and a jet of water under pressure serving to brush, scrape, orstrip the hull. Unfortunately, in order to be able to perform suchcleaning properly, the boat needs to be taken out of the water.

In order to take the boat out of the water, it is possible to use ahoist to life it onto a quay, but that operation is lengthy, difficult,and expensive, or else it is possible to position the boat in acareening place at high tide and wait for the tide to go down enough tobe able to work in air. Nevertheless, the tidal solution leaves littletime for cleaning the hull before the tide comes back in, and alsoassumes that the rise of the tide is sufficient to uncover the hullcompletely.

Documents WO 91/18785 and FR 2 723 908 disclose installations forcleaning boats that are afloat by using rotary brushes, similar to thosewhich exist for washing cars.

Document FR 2 369 964 also discloses an apparatus for cleaning andapparatus for rinsing the underwater portions of boat hulls.

The cleaning apparatus comprises a rotary brush actuated by a motor andplaced under a cover. A device enables jets of air to be directed intothe inside of the cover so as to reduce the loss of drive from the motorthat would otherwise occur if the brush were turning in water.Nevertheless, that cleaning apparatus does not make use of jets ofwater.

Furthermore, the rinsing apparatus comprises means for forming jets ofwater under high pressure mounted under an air-filled cover, in order toisolate said jets of water from the surrounding water. Nevertheless,that apparatus does not make provision for delivering jets of gas underlow pressure around said jets of rinsing water.

The two above-described apparatuses, each provided with a respectivecover, must consequently be applied against the hull to be cleaned,thereby limiting the area which can be cleaned on each pass of theapparatus.

Document GB 2 078 546 discloses apparatus for cleaning the underwaterstructures of offshore oil platforms that makes use simultaneously of ajet of water and a jet of air under pressure, the jet of air serving toreduce the noise of such apparatus greatly so as to improve the workingconditions of divers using the apparatus.

For this purpose, that apparatus has a nozzle for generating water athigh speed surrounded by an annular orifice through which air isejected.

Nevertheless, in such apparatus, the annular sleeve of air is presentonly for sound-insulation purposes and the cleaning jet of water alwaysoperates in water. Consequently, the diver must apply that apparatusvery closely (a few centimeters) to the underwater structure forcleaning in order to avoid the jet of water being excessively sloweddown by seawater. That limits the area of the surface which can becleaned on each pass of the apparatus. The total time required forcleaning is thus increased.

Finally, the abstract of Japanese patent No. 60-029394 disclosescleaning apparatus operating underwater and comprising firstly means forgenerating a jet of water under pressure through a tube, and secondlymeans for ejecting a jet of air under high pressure through an annularpassage surrounding said tube.

The jet of water under high pressure passes inside a cylinder whosewalls are formed by a layer of air, but which nevertheless containwater. The jet of water must therefore pass through a high density zoneof water in order to reach the hull, thereby considerably reducing itseffectiveness.

An object of the present invention is to develop apparatus and a methodfor cleaning underwater portions of a boat, making it possible to use aconventional nozzle for ejecting cleaning fluid under high pressure,which jet would be made ineffective for cleaning in the absence of thepresent invention, or at least less effective, by the presence of thewater around the boat. Another object of the invention is to clean alarge area of the hull on each pass of the apparatus, thereby reducingthe total time required for cleaning, while nevertheless performing highquality cleaning without taking the boat out of the water.

For this purpose, the invention provides apparatus for cleaning theportions of a boat that are underwater, the apparatus being of the typecomprising at least one cleaning unit having first generator means forgenerating a jet of cleaning fluid under high pressure, and second meansfor generating jets of gas.

In accordance with the invention, said first generator means enable acleaning fluid jet to be produced in the form of a fluid sheet, and saidsecond means comprise a manifold provided with a series of nozzlesconnected to a pressurizer and to a tank or a supply of gas, saidmanifold enabling jets of gas under low pressure to be generated so asto define a space around said cleaning fluid sheet in which spacedensity is considerably less than the density of the surrounding water,such as a space that is free or practically free from water, said spaceextending over the entire length of said cleaning fluid sheet from saidfirst generator means all the way to the area of said underwaterportions that is to be cleaned, said manifold being disposed beneathsaid first generator means in such a manner that its own longitudinalaxis extends substantially in the same vertical plane as the planecontaining the ejection axis of said cleaning fluid sheet, which sheetextends substantially vertically inside said space that is free orpractically free from water.

Thus, the sheet of fluid under high pressure which is delivered intosaid space does not waste energy pushing away the water in which theboat is immersed. Such apparatus enables the hull to be cleaned properlywhile placing the cleaning unit at a distance 5 centimeters (cm) to 30cm from the hull. This makes it possible to clean a large area of thehull in a single pass of the apparatus.

In addition, such apparatus is ecological since it makes use of cleaningmeans that are mechanical only.

According to other possible but non-limiting and advantageouscharacteristics of the invention:

-   -   said first generator means comprise a nozzle connected to a        compressor and to a tank or supply of cleaning fluid;    -   the apparatus includes means for generating a reaction force to        compensate the force that results from the ejection of the        cleaning fluid by said first means;    -   said means for generating a compensating reaction force consists        in additional means suitable for generating a jet of fluid in        the opposite direction to the jet of cleaning fluid;    -   the apparatus includes means for channeling the jets of gas        generated by said second means, such as a deflector disposed        longitudinally along said manifold;    -   said cleaning unit is mounted on an articulated arm allowing        said cleaning unit to be moved in three mutually perpendicular        directions, the displacement of said articulated arm being        controlled by a computer or a programmable controller as a        function of the profile of said underwater portions;    -   the apparatus comprises a plurality of cleaning units mounted on        an articulated support suitable for matching the shape of the        hull of a boat for cleaning, the support being mounted on at        least one guide rail provided on a quay or a pontoon beside        which the boat for cleaning is moored, said support being        capable of sliding along said guide rail under the control of a        computer or a programmable controller so as to move said        cleaning unit along the entire length of the boat and as a        function of the profile of said underwater portions; and    -   the apparatus includes sensors for measuring the shape of the        underwater portions for cleaning, said sensors being connected        to said computer or programmable controller in order to        servo-control the displacement of the cleaning unit(s) to the        shape of the hull.

The invention also provides a method of cleaning the underwater portionsof a boat by simultaneously projecting a jet of cleaning fluid underhigh pressure against said underwater portions together with jets ofgas.

This method is remarkable in that said jets of gas are generated at lowpressure beneath said jet of cleaning fluid in such a manner as todefine a space around said fluid jet in which space density isconsiderably less than the density of the surrounding water, such as aspace that is free or practically free from water, thereby isolating thefluid jet from the surrounding mass of water, said space extending overthe entire length of said cleaning fluid jet.

Preferably the fluid is hot or cold water or steam, and the gas is air.

In addition, the method can be implemented using the above-specifiedapparatus.

Other characteristics and advantages of the invention appear on readingthe following description of a preferred embodiment of the invention.This description is made with reference to the accompanying drawings, inwhich:

FIG. 1 is a diagram showing the cleaning unit of the apparatus of theinvention;

FIG. 2 is a diagrammatic section view of the sheet of cleaning fluid andthe space that is free or practically free from water, the section beingtaken on line II—II of FIG. 1;

FIG. 3 is a diagram of a first variant embodiment of the cleaningapparatus of the invention; and

FIG. 4 is a diagram of a second variant embodiment of the cleaningapparatus of the invention.

The apparatus of the invention comprises at least one cleaning unit 1 asshown in FIG. 1 for cleaning underwater portions 2 of a boat.

In the description below and in the claims, the term “underwaterportions” of a boat covers not only the hull, but also the keel, therudder, the propeller, and the propeller shaft. In the drawings, and forthe purposes of simplification, the underwater portions are representedby the hull of the boat.

The cleaning unit 1 of the invention may be of known type. It comprisesmeans 10 for generating a jet of cleaning fluid under high pressure. Byway of example, these means comprise an ejection nozzle 100 connected bya hose to a tank or a supply 102 of cleaning fluid, a compressor 101being interposed between said tank and said nozzle 100. As anindication, the high pressure at which the fluid is ejected is about120×10⁵ Pascals (Pa) to 200×10⁵ Pa.

The cleaning fluid is advantageously hot or cold water or steam.

Advantageously, the ejection nozzle is configured in such a manner thatthe jet of cleaning fluid is in the form of a sheet or a pencil of fluid103 and not merely a cylindrical jet. In other words, as seen from theside in FIG. 1, the sheet 103 is of a triangular, flared shape goingfrom the ejection end of the nozzle towards the hull 2 of the boat, andwhen seen end-on as in FIG. 2, it is oblong in shape having a width L₁that is small. This sheet 103 extends vertically.

By way of example, at the point of contact between the fluid sheet 103and the surface 2 for cleaning, the width L₁ of said sheet isapproximately 0.2 cm to 1 cm, while its height H is about 5 cm to 30 cm.In addition, the nozzle 100 is held at a distance lying in the range 5cm to 30 cm from the surface to be cleaned as a function of the energyneeded for dislodging the accumulated fouling and as a function of theprogramming of the means for moving the cleaning unit 1, which means aredescribed below. Consequently, the length L₂ of said sheet of watervaries likewise in the range approximately 5 cm to 30 cm.

Finally, the ejection nozzle 100 is advantageously provided on its rearface opposite from the face where the fluid sheet 103 is ejected withmeans 104 for generating a reaction force to compensate for the forcethat results from ejecting the cleaning fluid 103. These means 104 areconstituted, for example, by fluid ejection means serving to counter thereaction force exerted by the nozzle 100 under the effect of the thrustgenerated by the fluid sheet 103. The means 104 can be constituted by anozzle for ejecting a liquid or a gas taken from outside the cleaningunit 1 or by means of a pump for recirculating the seawater in which thecleaning unit 1 is immersed.

The cleaning unit 1 also comprises means 11 for generating a jet of gasat low pressure. In practice, it suffices for the pressure of the gas tobe greater than the pressure that exists at the depth in the water wherecleaning is taking place. By way of example, this pressure can be aboutone-tenth of a bar to a few bars (where 1 bar is equal to 10⁵ Pa).

These means 11 comprise a manifold 110 having a series of nozzles 111and connected to a gas tank or supply 113 via a pressurizer 112. The gasis advantageously air, for reasons of availability.

The bubbles and air jets 116 created by the manifold 110 serve to definea space 114 that is free or practically free of water (e.g. seawater ifthe boat is in a port, or fresh water if the boat is on a lake), andextends in a shape of cross-section that flares slightly upwards towardsthe surface of the water (see FIG. 2).

More precisely, the space or volume 114 contains a mixture of a smallamount of the water in which the boat is immersed and a large amount ofgas coming from the manifold 110. Consequently, inside this volume,density is much lower than the density of the surrounding water.

This manifold 110 is secured to the nozzle 100 and lies under it so thatits own longitudinal axis extends substantially in the same verticalplane as that containing the ejection axis of said nozzle 100, i.e. theejection axis of the fluid sheet 103, and the nozzles 111 of said ramplie beneath the fluid sheet 103. The fluid sheet 103 thus lies withinthe space 114 that is free or practically free of water, said space 114extending longitudinally over the entire length of said sheet 103 fromthe nozzle 100 to the surface of the hull 2 for cleaning.

As shown in FIG. 1, the manifold 110 may be hinged relative to thenozzle 100 in such a manner as to slope downwards a little at an angle αrelative to the ejection axis of the nozzle 100. This makes it possibleto direct the flow of gas so that it always surrounds the fluid sheet103 regardless of the point of the hull in front of which the cleaningunit 1 is located. The angle α is preferably determined so that the baseof the triangular jet of cleaning fluid is parallel to said manifold.

Optionally, in advantageous manner and as shown in FIG. 2, the manifold110 is provided with means for channeling the jets of gas 116, such asone of more deflectors 115 extending along its entire length, enablingthe bubbles and the jets of gas 116 to be channeled into the zonesurrounding the fluid sheet 103.

As shown in FIG. 3, in a first variant embodiment of the invention, thecleaning unit 1 is mounted on an articulated arm 3, itself connected toa fixed support 30 mounted on a quay or a pontoon 31. The articulatedarm 3 enables said unit 1 to be moved in three mutually perpendiculardirections. In other words, the unit 1 can move in three dimensions soas to follow the shape of the hull 2 for cleaning.

This articulated arm 3 can be controlled by a computer 4 or aprogrammable controller.

A second variant embodiment is shown in FIG. 4. In this case, aplurality of cleaning units 1 are mounted on a support 5 which isarticulated in such a manner as to be capable of matching the shape ofthe hull 2 of the boat for cleaning. This support 5 is mounted on atleast one guide rail 50 provided on the quay or the pontoon 31 besidewhich the boat for cleaning is moored. The support 5 can slide on saidguide rail 50 under the control of a computer or a programmablecontroller identical to that described above (but not shown in thefigures), so as to move said cleaning units 1 along the entire length ofthe boat.

Installations as shown in FIGS. 3 and 4 may also include sensors formeasuring the shape of the underwater portions 2 for cleaning, andconnect it to said computer or programmable controller in order toservo-control the displacement of the cleaning unit(s) 1 to the shape ofthe hull 2.

These measurement sensors may be of any known type, and in particularthey may be mechanical (feelers) or optoelectrical, for example similarto those used in certain automatic car-washing installations, and asdescribed in document EP 0 507 757, for example. The measurements takenare stored in a computer and transmitted to means for controlling thedisplacement of the articulated arm 3 or the articulated support 5.

After measurements have been taken by these sensors, it becomes possibleto clean the boat in a single pass of the apparatus shown in FIG. 4, orin three or more passes of the apparatus shown in FIG. 3.

The invention also provides a method of cleaning the underwater portionsof a boat. The method comprises the steps consisting in directing a jet(or sheet) of cleaning fluid under high pressure against said underwaterportions 2, while simultaneously ejecting jets of gas 116 beneath saidfluid jet so as to define a space 114 that is filled with very littlewater and with a great deal of gas, or with gas only, and in whichdensity is much less than the density of the surrounding water. Thisforms a space 114 around said cleaning fluid jet 103, which space isfree or practically free from water, thereby isolating said fluid jetfrom the surrounding mass of water. This space 114 extends over theentire length of said cleaning fluid jet 103.

The method may be implemented, for example, using the above-describedapparatus.

1. An apparatus for cleaning the portions of a boat that are underwater,the apparatus comprising at least one cleaning unit having firstgenerator means for generating a jet of cleaning fluid under highpressure, and second means for generating jets of gas, said firstgenerator means enabling a cleaning fluid jet to be produced in the formof a fluid sheet, and said second means including a manifold providedwith a series of nozzles connected to a pressurizer and to a tank or asupply of gas, said manifold enabling jets of gas under low pressure tobe generated so as to define a space around said cleaning fluid sheet inwhich space density is considerably less than the density of thesurrounding water, said space being free or practically free from waterand extending over the entire length of said cleaning fluid sheet fromsaid first generator means to the area of said underwater portions thatis to be cleaned, said manifold being disposed beneath said firstgenerator means in such a manner that its own longitudinal axis extendssubstantially in the same vertical plane as the plane containing theejection axis of said cleaning fluid sheet, which sheet extendssubstantially vertically inside said space that is free or practicallyfree from water.
 2. The cleaning apparatus according to claim 1, whereinsaid first generator means includes a nozzle connected to a compressorand to a tank or supply of cleaning fluid.
 3. The cleaning apparatusaccording to claim 1, further comprising means for generating a reactionforce to compensate the force that results from the ejection of thecleaning fluid by said first means.
 4. The cleaning apparatus accordingto claim 3, wherein said means for generating a compensating reactionforce includes additional means for generating a jet of fluid in theopposite direction to the jet of cleaning fluid.
 5. The cleaningapparatus according to claim 1, further comprising means for channelingthe jets of gas generated by said second means including a deflectordisposed longitudinally along said manifold.
 6. The cleaning apparatusaccording to claim 1, wherein said cleaning unit is mounted on anarticulated arm allowing said cleaning unit to be moved in threemutually perpendicular directions, the displacement of said articulatedarm being controlled by a computer or a programmable controller as afunction of the profile of said underwater portions.
 7. The cleaningapparatus according to claim 6, further comprising sensors for measuringthe shape of the underwater portions for cleaning, said sensors beingconnected to said computer or programmable controller in order toservo-control the displacement of the cleaning unit(s) to the shape ofthe hull.
 8. The cleaning apparatus according to claim 1, wherein saidapparatus includes a plurality of cleaning units mounted on anarticulated support suitable for matching the shape of the hull of aboat for cleaning, the support being mounted on at least one guide railprovided on a quay or a pontoon beside which the boat for cleaning ismoored, said support being capable of sliding along said guide railunder the control of a computer or a programmable controller so as tomove said cleaning unit along the entire length of the boat and as afunction of the profile of said underwater portions.
 9. A method ofcleaning the underwater portions of a boat comprising the step ofsimultaneously projecting a jet of cleaning fluid under high pressureagainst said underwater portions together with jets of gas, said jets ofgas being generated at low pressure beneath said jet of cleaning fluidin such a manner as to define a space around said fluid jet in whichspace density is considerably less than the density of the surroundingwater so as to be free or practically free from water, thereby isolatingthe fluid jet from the surrounding mass of water, said space extendingover the entire length of said cleaning fluid jet.
 10. The cleaningmethod according to claim 9, wherein the fluid is water or steam, andthe gas is air.
 11. The cleaning method according to claim 9, saidmethod being implemented using an apparatus comprising at least onecleaning unit having first generator means for generating a jet ofcleaning fluid under high pressure, and second means for generating jetsof gas, said first generator means enabling a cleaning fluid jet to beproduced in the form of a fluid sheet, and said second means including amanifold provided with a series of nozzles connected to a pressurizerand to a tank or a supply of gas, said manifold enabling jets of gasunder low pressure to be generated so as to define a space around saidcleaning fluid sheet in which space density is considerably less thanthe density of the surrounding water, said space being free orpractically free from water and extending over the entire length of saidcleaning fluid sheet from said first generator means to the area of saidunderwater portions that is to be cleaned, said manifold being disposedbeneath said first generator means in such a manner that its ownlongitudinal axis extends substantially in the same vertical plane asthe plane containing the ejection axis of said cleaning fluid sheet,which sheet extends substantially vertically inside said space that isfree or practically free from water.